Apparatus for producing a curly puff extrudate

ABSTRACT

A process and apparatus for the production of a spiral or coil shaped puffed extrudate. A tube or other peripheral containment vessel is placed at the exit end of an extruder die. A force or resistance is then applied on the extrudate downstream of the glass transition point, thereby causing the extrudate to back up and coil in the containment vessel.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to the production of a spiral shaped puffextrudate and, in particular, to confining the extrudate in a tube orlike peripheral containment vessel while applying a force or resistanceon the extrudate downstream of the extrudate's glass transition point.The downstream force or resistance causes the otherwise linear extrudateto “back-up” into the containment vessel, thus coiling into the spiralor curl shape.

2. Description of Related Art

The production in the prior art of a puffed extruded product, such assnacks produced and marketed under the Cheetos™ brand label, typicallyinvolves extruding a corn meal or other dough through a die having asmall orifice at extremely high pressure. The dough flashes or puffs asit exits the small orifice, thereby forming a puff extrudate. Thetypical ingredients for the starting dough may be, for example, cornmeal of 41 pounds per cubic foot bulk density and 12 to 13.5% watercontent by weight. However, the starting dough can be based primarily onwheat flour, rice flour, soy isolate, soy concentrates, any other cerealflours, protein flour, or fortified flour, along with additives thatmight include lecithin, oil, salt, sugar, vitamin mix, soluble fibers,and insoluble fibers. The mix typically comprises a particle size of 100to 1200 microns.

The puff extrusion process is illustrated in FIG. 1, which is aschematic cross-section of a die 12 having a small diameter exit orifice14. In manufacturing a corn-based puffed product, corn meal is added to,typically, a single (i.e., American Extrusion, Wenger, Maddox) or twin(i.e., Wenger, Clextral, Buhler) screw-type extruder such as a model X25 manufactured by Wenger or BC45 manufactured by Clextral of the UnitedStates and France, respectively. Using a Cheetos like example, water isadded to the corn meal while in the extruder, which is operated at ascrew speed of 100 to 1000 RPM, in order to bring the overall watercontent of the meal up to 15% to 18%. The meal becomes a viscous melt 10as it approaches the die 12 and is then forced through a very smallopening or orifice 14 in the die 12. The diameter of the orifice 14typically ranges between 2.0 mm and 12.0 mm for a corn meal formulationat conventional moisture content, throughput rate, and desired extrudaterod diameter or shape. However, the orifice diameter might besubstantially smaller or larger for other types of extrudate materials.

While inside this small opening 14, the viscous melt 10 is subjected tohigh pressure and temperature, such as 600 to 3000 psi and approximately400° F. Consequently, while inside the small orifice 14, the viscousmelt 10 exhibits a plastic melt phenomenon wherein the fluidity of themelt 10 increases as it flows through the die 12.

It can be seen that as the extrudate 16 exits the orifice 14, it rapidlyexpands, cools, and very quickly goes from the plastic melt stage to aglass transition stage, becoming a relatively rigid structure, referredto as a “rod” shape if cylindrical, puffed extrudate. This rigid rodstructure can then be cut into small pieces, further cooked by, forexample, flying, and seasoned as required.

Any number of individual dies 12 can be combined on an extruder face inorder to maximize the total throughput on any one extruder. For example,when using the twin screw extruder and corn meal formulation describedabove, a typical throughput for a twin extruder having multiple dies is2,200 lbs., a relatively high volume production of extrudate per hour,although higher throughput rates can be achieved by both single and twinscrew extruders. At this throughput rate, the velocity of the extrudateas it exits the die 12 is typically in the range of 1000 to 4000 feetper minute, but is dependent on the extruder throughput, screw speed,orifice diameter, number of orifices and pressure profile.

As can be seen from FIG. 1, the snack food product produced by suchprocess is necessarily a linear extrusion which, even when cut, resultsin a linear product. Consumer studies have indicated that a producthaving a similar texture and flavor presented in a “curl,” “spiral,” or“coil spring” shape (all of which terms are used synonymously byApplicant herein) would be desirable. An example of such spiral shape ofsuch extrudate is illustrated in FIG. 2, which is a perspective view ofone embodiment of a spiral or curl shaped puffed extrudate 20. Theembodiment illustrated in FIG. 2 is an extrudate with a relatively tightpitch, short diameter, and cut at approximately four turns or spirals.It should be understood that when referring to a curl, spiral, or coilspring shaped puffed extrudate, however, Applicant intends that thepitch (which can be a left hand or right hand pitch) and diameter of thecurl or spiral in addition to the rod (or other shape) diameter andpiece length can each vary independently to provide a wide variety ofproducts. Unfortunately, the high volume process described aboveprovides unique challenges in producing such shape 20.

The usual method for imparting a spiral shape in an extrudate, such aswith spiral shaped pasta, involves forcing the dough through a spiralshaped die orifice. As can be readily understood, such solution wouldnot work with a puffed product that is in a plastic melt stage insidethe die and produced at the velocity described above, since the productwould have no memory of the imparted spiral shape upon exiting the die.In fact, it has been found that it is extremely difficult tomeaningfully manipulate the melt as it passes through the die in orderto induce an extrudate to wind in free space, by, for example, atemperature differential from one side of the die to the other, withoutsubstantially reducing the flow rate of the melt through the die.

Another prior art method for imparting twists or curls in the doughinvolves using an extruder with rotating nozzles. This process, however,is only viable when the extrudate retains a very pliable form. Further,extrusion by way of rotating nozzles typically, again, requires agreatly reduced throughput rate as compared with the relatively highvolume production desirable with the prior art linear products.

To further complicate the matter, a larger surface area is required onthe extruder face for the same number of individual dies when extrudinga curled product versus a linear product, since the space between eachdie as between a linear product and a curled product must necessarily beincreased to allow for the diameter of the spiral. By way of example, anextruder face may under prior art conditions accommodate 28 individualdies running at 80 lbs. per hour per each die, thereby producing a 2,240lb. per hour throughput for the entire extruder. In order totheoretically produce the curl shaped extrudate 20 shown in FIG. 2, thesame extruder face might only accommodate, for example, 4 individualdies. By way of further example, if it is necessary to slow thethroughput rate to less than 30 lbs. per hour per die in order to impartsome spiral shape on the extrudate by manipulating the melt inside thedie, this reduces the total throughput for that extruder to only 120lbs. per hour. Thus, by converting an extruder to manipulate the meltinside the die and imparting a spiral shape, the extruder maintains onlyabout 5% of the throughput rate as compared to the standard linearproduction, even though the throughput for each individual die isreduced to about 38% of the previous throughput rate. The problembecomes even more pronounced if the extrudate throughput is reduced toeven lower levels.

It can be easily understood that any prior art solution that requiresthe substantial reduction in the throughput of the extrudate, therefore,is not an acceptable alternative when, for example, twenty extrudersmust be used to match the throughput of a single extruder when comparedwith a linear production line. Forcing the extrudate into some spiralshaped former upon exiting the die is also not practical due to thebrittle consistency of the extrudate after it drops below its glasstransition temperature. Also, such spiral shaped former could becomeeasily clogged, thereby requiring stopping the entire production line.

Consequently, a need exists for developing a method and apparatus thatcan impart a spiral or curl shape in a puff extrudate while alsomaintaining an efficient throughput rate of the product through theextruder. Ideally, such invention should be readily adaptable toexisting extruders and dies, require little or minimal modification tosuch equipment, allow for traditional face cutting, and introduce as fewcollateral processing issues as possible when integrated into theoverall production line.

SUMMARY OF THE INVENTION

The proposed invention comprises introducing the extrudate as it exitsthe extruder die into a containment tube or other peripheral containmentvessel that is generally axially oriented with the flow path of theextrudate and has a diameter that approximates the intended diameter ofeach curl. A slight pressure, force, or resistance is then applied onthe extrudate downstream of the glass transition point. This resistancecauses the extrudate to “back up” and, in essence, coil inside theperipheral containment vessel.

The resistance can be accomplished by any number of means. For example,a blocking element can be placed in front of the containment tube,either outside of or integral to the tube. A hole can be drilled in thecontainment tube and either a pressure applied or a vacuum appliedthrough such hole, either of which need only be of such magnitude toeffect a change in the resistance on the extrudate sufficient to beginthe coiling process. A blocking flap under spring tension can also beused, or any number of small obstructions or means of applying a forceon the extrudate.

Such a device can be easily fitted to the exit of an extruder die at oneend and to a circular extruder face at the other end, thereby allowingfor a simple and inexpensive retrofit to existing machinery and allowingfor face cutting. Changes in the containment vessel and changes in themethod of applying resistance can be used to adjust the pitch anddiameter of the curl. Economically high throughput rates can beachieved, thus allowing for efficient utilization of existing extruderproduction lines without requiring additional extruders to maintain lineproduction rates.

The above as well as additional features and advantages of the presentinvention will become apparent in the following written detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives and advantages thereof, willbe best understood by reference to the following detailed description ofillustrative embodiments when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a schematic cross-section of a prior art puff extrudate die;

FIG. 2 is a perspective view of one embodiment of the desired puffextrudate product;

FIG. 3 is a perspective view in elevation of one embodiment of thepresent invention;

FIG. 4 is a perspective view in elevation of an alternative embodimentof the present invention;

FIG. 5 is a perspective view in elevation of an alternative embodimentof the invention;

FIG. 6 is a perspective view in elevation of an alternative embodimentof the invention; and

FIG. 7 is a perspective view in elevation of an embodiment of theinvention incorporated into a multiple die and circular face cuttingarrangement.

DETAILED DESCRIPTION

FIG. 3 is a perspective view in elevation of one embodiment of theinvention which also shows the extrudate 20 in phantom inside thecontainment tube 30. Corresponding reference numerals are used torepresent corresponding elements throughout the figures shown in thisapplication unless otherwise indicated.

The extrudate 20 exits the small orifice 14 of the die 12 in the samemanner as described in the prior art. Again, the diameter of the orifice14 is dependent on the specific dough formulation, throughput rate, anddesired rod (or other shape) diameter, but is preferred in the range of1 mm to 14 mm. (The orifice 14 diameter is also dependent on the meanparticle size of the corn meal or formula mix being extruded.) The tube30 is shown centered over the orifice 14 and axially oriented with theextrudate flow. However, it should be understood that the tube 30 couldbe off-center from the orifice 14 and canted some degrees from an axialorientation. It should also be understood that the orifice 14 need notbe circular, but could be any number of shapes, such as star shaped,hexagonal, square, etc . . . .

If no force or resistance were applied to extrudate 20, it would proceeddown the length of the containment tube 30 in a straight rod or linearformation, as with the prior art. However, in the embodiment shown inFIG. 3, a spring loaded flapper 32 provides a slight, and oscillating,resistance on the extrudate 20 at some point downstream of the glasstransition point for the extrudate 20. As used herein, the glasstransition point is that point where the extrudate turns from a liquidor plastic phase to solid or glassy phase after puffing out of theorifice 14, thereby resulting in a relatively brittle end product. Theglass transition point is generally very close to the exit of theorifice 14, and is certainly within a few millimeters of such pointduring the production of the example corn products previously describedherein. This slight resistance applied downstream of the glasstransition point causes the extrudate 20 to seek the path of leastresistance and begin backing up into the containment tube 30 untilforming the coils illustrated, thereby adapting the circular shape ofthe containment tube 30. Consequently, the velocity of the extrudate 20in the direction of tube 30 opening is reduced.

The pitch of the spiral can be controlled by adjusting the force appliedon the extrudate by the flapper 32. In the embodiment shown, this isaccomplished by an adjustment means 34 which controls the tension on aspring 36. The spring 36, which can be a compression spring, extensionspring or any number of actuators, both mechanical and electrical, inturn pushes the flapper 32 into a cavity 38 cut into the containmenttube 30.

The flapper 32 arrangement with the cavity 38 provides the additionalbenefit of allowing exhausting of excess water or steam out of thecontainment tube 30. Further, the spring loaded flapper 32 provides ameans for applying resistance to the extrudate 20 while also allowingfor clearing of the containment tube 30 in the event of excess extrudatebuildup.

As with the other embodiments shown, the diameter of the tube 30 canvary depending on the diameter of the curl that is desired. Typically,an inside diameter of the tube 30 between 0.5 inch and 4 inch ispreferable. The length of the tube 30 is not critical, as long as itallows for the application of the resistance described sufficientlydownstream of the glass transition point to produce the coiling effect.Tubes having an overall length of 0.75 inch to 12 inches have been foundto be acceptable.

Another embodiment of the present invention is found in FIG. 4, whichshows a containment tube 40 with alternating tines 42, 44 at the exitend of the tube 40. Half of the tines 42 are merely parallel extensionsof the tube 40. The other half of the tines 44 are bent slightly inward,thereby providing the resistance necessary to begin the curling of theextrudate within the containment tube 40.

FIG. 5 shows another embodiment of the present invention incorporating asmall orifice 52 cut into the containment tube 50. Pressurized air or,alternatively, a vacuum may be introduced at the orifice 52. Thedifferential pressure thereby produced is sufficient to again causeenough resistance within the containment tube to cause the extrudate tocurl within the tube 50. For example, at a throughput rate of 300 lbs.per hour using a die orifice diameter of 2.0 mm and tube 50 diameter of1 inch, the introduction of a pressure in the range of 5 to 100 psig ora vacuum in the range of −0.5 torr to −258.5 torr have both been foundeffective in producing the desired phenomenon.

FIG. 6 shows another alternative embodiment to the proposed inventioninvolving a curved containment tube 60. The curve or bend founddownstream on the containment tube 60 again creates the desiredresistance on the extrudate required to begin the curling within thecontainment tube 60. Depending on the throughput rate of the extrudateand the physical proportions of the extrudate, a curve in thecontainment tube of anywhere from 2° to 90° has been demonstrated toproduce the desired effect. The same effect can be achieved using astraight tube axially canted slightly from the extrudate flow path, suchthat the initial contact of the extrudate with the inner wall of thetube provides the resistance required.

It should be understood that the various embodiments shown in FIGS. 3-6are provided merely as examples of means by which a downstreamresistance or pressure can be applied to the extrudate while suchextrudate is bound by a containment tube or other peripheral containmentvessel. Any number of shapes of containment vessels can be used, such asa containment vessel having rectangular, square, oval, or triangularsidewalls as opposed to a circular tube. The use of a square ortriangular containment vessel typically produces a spiral similar tothat produced by a round containment vessel. An oval containment vesselcan produce a curled product that generally adopts the overall ovalshape of the vessel. The containment vessel need not be a continuousenclosure. For instance, it can also consist of a plurality of members,such as rod shaped members, which generally form the skeleton or wireframe shape of a continuous-walled containment vessel, such as a pipe.

It should be understood that using the same principles previouslydisclosed, a rectangular containment vessel can be used having a widthonly slightly larger than the diameter of the extrudate to produce asinusoidal shaped extrudate as opposed to a curly extrudate. When aresistance is applied to an extrudate in such containment vessel, asinusoidal shape is formed, as the extrudate oscillates back and forthwithin the narrow rectangular shape. The wavelength of this sinusoidalshape can be varied depending on the resistance applied and the velocityof the extrudate. The height or amplitude of the sinusoidal shape isapproximately one-half the interior height of the rectangularcontainment vessel.

Regardless of the shape of the containment vessel used, any number ofmeans of applying the resistance can also be used, including theintroduction of any physical resistance or any other means to redirectthe extrudate stream sufficient to cause the extrudate to back up insidethe containment tube or peripheral containment vessel. An area ofincreased resistance in a straight tube, for example, could produce thedesired effect. The resistance need not be applied from a point withinthe containment vessel, but can be applied outside the containmentvessel as well.

It has been found that traditional throughput rates through existingdies may be maintained using any of the embodiments illustrated anddiscussed above. In fact, throughput rates in excess of traditionalextrusion throughputs, for example in the range of 400 lbs. per hourthrough a 2.0 mm diameter die, have been achieved while stillmaintaining the continuous curls flowing from each containment tube.Consequently, a lesser number of extruder dies can be used toaccommodate the spiral diameter while still maintaining an effectivethroughput rate when a number of dies are used in combination or seriesalong an extruder face.

FIG. 7 illustrates a perspective view of one embodiment of the inventioninvolving a number of dies 12 in series attached to a number ofcontainment tubes 70. The exit end of each containment tube 70 isattached to an extruder face 72. This arrangement then permits theattachment to the extruder face of a circular cutting apparatus 74having a number of individual cutting blades 76. Such an arrangement isshown with ten individual extruder dies 12 connected to ten containmenttubes 70, and permits overall throughput rates through the extruderequal to the throughput rates previously described for prior art puffedrod production using the methods described above.

Although not shown in FIG. 7, the containment tube 70 and extruder face72 configuration can be designed such that the dies 12 are allowed tovent until specific conditions are met (such as extrudate bulk density,specific mechanical energy, moisture content, screw speed, and diepressure), then the containment tube 70 can be rotated over the dies 12by means of an additional rotatable plate (not shown) between the tubes70 and the dies 12.

It should further be understood that more than one die can be routedinto a single containment tube. For example, a containment tube canreceive the exit extrudate from two nearby die orifices. Further, diesproducing any number of shapes, such as a star or square cross sectionor more complex shapes, such as a cactus or pepper shape, can be usedwith the invention.

Any number of various types of extruders can be used with the invention,including twin screw and single screw extruders of any length andoperating at a wide range of rpm. Further, while the process has beendescribed with regard to a corn-based product, it should be understoodthat the invention can be used with any puffed extrudate, includingproducts based primarily on wheat, rice, or other typical proteinsources or mixes thereof. In fact, the invention could have applicationsin any field involving extrusion of a material that quickly goes througha glass transition stage after being extruded through a die orifice.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

What is claimed is:
 1. An apparatus for producing a sinusoidalextrudate, said apparatus comprising: an extruder die; a rectangularperipheral containment vessel attached to said die, wherein saidrectangular peripheral containment vessel comprises an interior widthapproximately equivalent to the cross-sectional diameter of theextrudate contained therein; and a means for imparting a resistance onan extrudate stream exiting from said die, wherein such resistance isapplied downstream of the glass transition point of the extrudate,thereby causing the extrudate stream to oscillate inside said peripheralcontainment vessel.
 2. The apparatus of claim 1 wherein the peripheralcontainment vessel comprises a tube having a rectangular cross-section.3. The apparatus of claim 1 wherein the peripheral containment vessel isgenerally axially oriented in relation to the extrudate stream.
 4. Theapparatus of claim 1 wherein the means for imparting a resistancecomprises a flapper attached to the exterior of said peripheralcontainment vessel and extending into said containment vessel through anopening cut in the containment vessel.
 5. The apparatus of claim 1wherein the means for imparting a resistance on a extrudate streamcomprises a restriction at least one point along the peripheralcontainment vessel.
 6. The apparatus of claim 1 wherein the means forimparting a resistance on an extrudate stream comprises the introductionof a pressurized gas into the peripheral containment vessel.
 7. Theapparatus of claim 1 wherein the means for imparting a resistance on anextrudate stream comprises creating a vacuum within the peripheralcontainment vessel.
 8. The apparatus of claim 1 further comprising: anextruder die face attached to an exit end of a peripheral containmentvessel; and a circular die cutting device attached to said extruderface.
 9. An apparatus for producing a spiral extrudate, said apparatuscomprising: an extruder die; a peripheral containment vessel attached tosaid die; and a means for imparting a resistance on an extrudate streamexiting from said die, wherein such resistance is applied downstream ofthe glass transition point of the extrudate, thereby causing theextrudate stream to coil inside said peripheral containment vessel. 10.The apparatus of claim 9 wherein the peripheral containment vesselcomprises a tube.
 11. The apparatus of claim 9 wherein the peripheralcontainment vessel is generally axially oriented in relation to theextrudate stream.
 12. The apparatus of claim 9 wherein the means forimparting a resistance comprises a flapper attached to the exterior ofsaid peripheral containment vessel and extending into said containmentvessel through an opening cut in the containment vessel.
 13. Theapparatus of claim 9 wherein the means for imparting a resistance on aextrudate stream comprises a restriction at least one point along theperipheral containment vessel.
 14. The apparatus of claim 9 wherein themeans for imparting a resistance on an extrudate stream comprises theintroduction of a pressurized gas into the peripheral containmentvessel.
 15. The apparatus of claim 9 wherein the means for imparting aresistance on an extrudate stream comprises creating a vacuum within theperipheral containment vessel.
 16. The apparatus of claim 9 furthercomprising: an extruder die face attached to an exit end of a peripheralcontainment vessel; and a circular die cutting device attached to saidextruder face.